Thermal water is the name given to water that comes to the surface at a temperature of 5ºC higher than the average annual temperature for that given area. The benefits of thermal waters derive from the existence of minerals that dissolve in the water.

Minero-medicinal water
This is water that contains minerals with therapeutic qualities obtained by means of diverse biological and geological processes. Thermal waters are also minero-medicinal, but not all minero-medicinal waters are thermal, as some are cold.

Classification of thermal waters:

Depending on the temperature of subterranean water, different minerals will be dissolved. Thermal waters can therefore be classified on the basis of location, temperature, geological origin and chemical and mineral composition.

Diverse classifications exist based on origin, temperature or chemical composition. The following is a summary of types of water according to mineral composition, as well as indications as to how they can be applied:

Classification by mineral composition:

Bicarbonated waters:
Cold, alkaline water with low mineralization. Its use is through ingestion, acting on the metabolism in such as way as to alkalinize the gastric PH if taken on an empty stomach, thus reducing acidity and aiding the digestive process.

The most common waters of this kind are:
Sodium bicarbonate: applied to treat gastric ailments such as intestinal hypermotility, duodenal ulcers, diarrhoea and liver and kidney problems.
Calcium bicarbonate: aids digestion.
Mixed bicarbonate: aids digestion.
Sulphur bicarbonate: used in cases of liver intoxication and constipation.
Chloride bicarbonate: used for rheumatic complaints.

Chloride waters:
Waters that contain a predominance of chloride. They are used to treat dermatological complaints, as they increase the natural defences of the skin. They also have an anti-inflammatory effect if they contain sodium.

Ferruginous waters:
Waters that mainly contain iron, although they often also contain bicarbonates or sulphates.

They are used in the treatment of ferropenic anaemia and other kinds of anaemia, as this type of water is considered to be a reconstituent. Also used to treat obesity, rheumatism, liver and bile disorders, certain skin problems and childhood development disorders.

Sulphurous waters:
These are found in muddy areas and are used to treat joint complaints such as rheumatic and post-operative problems affecting the locomotory apparatus, anaemia, neuralgias, pruriginous dermatosis, allergic inflammations and respiratory problems such as asthma. Sulphurous waters are also effective in cases of hypertension and haemoptysis.

Sulphated waters:
These can be sub-classified as follows:

Sodium and magnesium sulphates: they have powerful laxative properties. Other uses include skin complaints, pruritus and certain types of medicinal or food intoxication.
Calcium sulphate: used to treat gastric, intestinal, liver and bile disorders.
Chloride sulphate: effective in the treatment of digestive complaints, gastritis, constipation and hepatic insufficiency.

This type of water is generally ingested but can also be applied by other means.

Radioactive waters:
These are waters that contain radon gas, which is naturally radioactive. Used in hydrotherapy, this type of water has no negative effects; on the contrary, it is used to treat ailments affecting the neurovegetative system, endocrine complaints and alterations of the autoimmune system, as well as chronic respiratory, rheumatic and skin problems.

Sulphured waters:
These are waters that predominantly contain sulphur, which gives them a characteristic smell of rotten eggs. They are mainly used to treat rheumatic disorders, skin problems such as eczema, queratosis, psoriasis and pruritus, and chronic respiratory complaints such as laryngitis, rhinitis, bronchitis and asthma.